In rotary lawnmowers, a blade housed within a housing that is open at the bottom is caused to rotate over grass, thereby cutting it. Such lawnmowers include those having a format in which a bagging mode is employed. In lawnmowers in which a bagging mode is employed, the grass cut by the blade (i.e. cut grass) is stored in a bag or other container for cut grass. All of the cut can grass can be disposed of to give the cutting site a neat appearance, and these mowers are frequently employed on golf courses and the like. An example lawnmower in which a bagging mode is employed is disclosed in Japanese Patent No. 3771507.
The lawnmower disclosed in Japanese Patent No. 3771507 can be switched by hand between a bagging mode, in which the shutter is fully open, and the cut grass is stored in a cut-grass container; a mulching mode, in which the shutter is fully closed, and the cut grass is discharged to the area below the housing; and intermediate modes between the bagging mode and the mulching mode, in which the shutter is manually set to any desired degree of opening.
The housing is provided with a conduit through which cut grass is discharged. The cut-grass container can be attached to this discharge conduit. A shutter is positioned within the housing. The shutter can revolve along the inner circumferential surface of the housing, where the center of revolution is the center of rotation of the blade. The degree of opening of the discharge conduit for cut grass is adjusted by the shutter. An operating lever is attached to the shutter via an arm. The operating lever can be operated and made to revolve, where the center of revolution is the center of rotation of the blade. The angle of revolution (angle of operation) of the operating lever is the same as the angle of revolution (angle of opening or closing) of the shutter.
The angle of opening or closing when the shutter is swung from completely open to completely closed is determined according to the size of the housing and of the aperture of the discharge conduit for cut grass. The aperture is relatively large, and the angle of opening and closing must therefore also be large. On the other hand, the operating angle when the operating lever is operated from fully open to fully closed, and the range of motion of the arm are subject to the limitations resulting from the positions of other members in the lawnmower. In other words, the operating angle and the range of motion of the arm must be kept within a range such that the operating lever does not interfere with the engine or other members.
If the lawnmower is large in size, the housing will be large, so that such interference will not occur. However, when the lawnmower is small in scale, the housing is small. There is therefore room for improvement in adequately allowing for the operating angle necessary for opening and closing shutter within the limits of these constraints.